3,389 research outputs found
Determination of quantum symmetries for higher ADE systems from the modular T matrix
We show that the Ocneanu algebra of quantum symmetries, for an ADE diagram
(or for higher Coxeter-Dynkin systems, like the Di Francesco - Zuber system)
is, in most cases, deduced from the structure of the modular T matrix in the A
series. We recover in this way the (known) quantum symmetries of su(2) diagrams
and illustrate our method by studying those associated with the three genuine
exceptional diagrams of type su(3), namely E5, E9 and E21. This also provides
the shortest way to the determination of twisted partition functions in
boundary conformal field theory with defect lines.Comment: 30 pages, 16 figures. Several misprints have been corrected. We added
several references and the appendix has been enlarged (one section on
essential paths and one section devoted to open problems). This article will
appear in the Journal of Mathematical Physic
Pulse shape discrimination performance of Inverted Coaxial Ge detectors
We report on the characterization of two inverted coaxial Ge detectors in the
context of being employed in future Ge neutrinoless double beta
() decay experiments. It is an advantage that such detectors
can be produced with bigger Ge mass as compared to the planar Broad Energy Ge
detectors (BEGe) that are currently used in the GERDA decay
experiment. This will result in lower background for the search of
decay due to a reduction of cables, electronics and holders.
The measured resolution near the Ge Q-value at 2039 keV is 2.5 keV and
their pulse-shape characteristics are similar to BEGe-detectors. It is
concluded that this type of Ge-detector is suitable for usage in Ge
decay experiments
ON THE PROBLEM OF LIQUID ENTRAINMENT
THe problem of liquid entrainmment by a gas phase is considered with the purpose of gathering, presentinf, and correlating available information which may be useful for predicting the liquid carry-over in a boiling water reactor at high pressure. Correlations which predict water carryover as a function of pressure, of the height of the vapor dome, and of the vapor mass flow rate are presented and discussed. Because entrainment depends upon the hydrodynamic conditions and upon the expansion of a two-phase bubbling mixture, the transportation 0f vapor through such mixtures is also discussed. Equations which relate the volumetric vapor fraction to the reduced (superficial) vapor velocity in bubbling at high pressures are presented, and some inconsistencies are noted. Experimental data and correlations which predict the location of the liquid-vapor interface in bubbling at high pressures are also givna. Experimental data on water carry-over at high pressures reported in the literature are summarized. The problems of drop formation for bursting bubbles and of drop ballistics are discussed together with some analytical formulations of the entrainment problem. The bibliography may prove useful as a source of additional information on the problems of carry- over, corrosion and on the purity of steam and of water at high pressures. (auth
From modular invariants to graphs: the modular splitting method
We start with a given modular invariant M of a two dimensional su(n)_k
conformal field theory (CFT) and present a general method for solving the
Ocneanu modular splitting equation and then determine, in a step-by-step
explicit construction, 1) the generalized partition functions corresponding to
the introduction of boundary conditions and defect lines; 2) the quantum
symmetries of the higher ADE graph G associated to the initial modular
invariant M. Notice that one does not suppose here that the graph G is already
known, since it appears as a by-product of the calculations. We analyze several
su(3)_k exceptional cases at levels 5 and 9.Comment: 28 pages, 7 figures. Version 2: updated references. Typos corrected.
su(2) example has been removed to shorten the paper. Dual annular matrices
for the rejected exceptional su(3) diagram are determine
Lorentz and CPT Invariance Violation In High-Energy Neutrinos
High-energy neutrino astronomy will be capable of observing particles at both
extremely high energies and over extremely long baselines. These features make
such experiments highly sensitive to the effects of CPT and Lorentz violation.
In this article, we review the theoretical foundation and motivation for CPT
and Lorentz violating effects, and then go on to discuss the related
phenomenology within the neutrino sector. We describe several signatures which
might be used to identify the presence of CPT or Lorentz violation in next
generation neutrino telescopes and cosmic ray experiments. In many cases,
high-energy neutrino experiments can test for CPT and Lorentz violation effects
with much greater precision than other techniques.Comment: 27 pages, 8 figure
Kaon physics with a high-intensity proton driver
We study opportunities for future high-precision experiments in kaon physics
using a high-intensity proton driver, which could be part of the front-end of a
muon storage ring complex. We discuss in particular the rare decays
, , , and
lepton-flavour violating modes such as and . The
outstanding physics potential and long-term interest of these modes is
emphasized. We review status and prospects of current and planned experiments
for the processes under consideration, and indicate possible improvements and
strategies towards achieving the necessary higher sensitivity. Finally, we
outline the machine requirements needed to perform these high-precision kaon
experiments in the context of a muon storage ring facility.Comment: 26 pages, 12 figures; report of the kaon physics working group for
the ECFA studies on neutrino factory and muon storage rings at CERN, G.
Buchalla (convener); references update
Long-term variability of CO2 and O in the Mars upper atmosphere from MRO radio science data
We estimate the annual variability of CO2 and O partial density using approximately 6years of Mars Reconnaissance Orbiter (MRO) radio science data from August 2006 to January 2012, which cover three full Martian years (from the northern hemisphere summer of 28 to the northern hemisphere summer of 31). These two elements are the dominant species at the MRO periapsis altitude, constituting about 70-80% of the total density. We report the recovered annual cycle of CO2 and the annual and seasonal cycle of O in the upper atmosphere. Although no other observations are available at those altitudes, our results are in good agreement with the density measurements of the Mars Express Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars, which uses stellar occultations between 60 and 130km to determine the CO2 variability, and with the Mars Global Reference Atmospheric Model 2010 for the O annual and seasonal variabilities. Furthermore, the updated model provides more reasonable MRO drag coefficients (CD), which are estimated to absorb mismodeling in the atmospheric density prediction. The higher content of dust in the atmosphere due to dust storms increases the density, so the CDs should compensate for this effect. The correlation between the drag coefficient and the dust optical depth, measured by the Mars Odyssey Thermal Emission Imaging System (THEMIS) instrument, increases from 0.4 to 0.8 with the a priori and adjusted models, respectively. The trend of CDs not only confirms a substantial improvement in the prediction of the atmospheric density with the updated model but also provides useful information for local dust storms, near MRO periapsis, that cannot be measured by the opacity level since THEMIS does not always sample the southern hemisphere evenly
A search for double beta decays of tin isotopes with enhanced sensitivity
A search for the various double beta decay modes of 124Sn and 112Sn has been
performed on 75 kg.days of data. New half-life limits for excited states in
124Sn have been obtained including a lower limit for the decay into the first
excited 2+ state of 124Te of T_half > 0.87e20 yrs (90% CL) and into the first
excited 0+ state of T_half > 1.08e20 yrs (90% CL). Ground state and excited
state transitions of 112Sn have also been experimentally explored. A limit for
the 2 neutrino double electron capture of T_half > 1.8e19 yrs (90% CL) is
obtained. The non-observation of de-excitation gammas from the 0+ at 1888.5keV
results in a lower half-life limit on the 0 neutrino double electron capture
decay of 112Sn of T_half > 0.8e19 yrs (90% CL), despite a possible resonant
enhancement of the decay rate due to degenerated states.Comment: 6 pages, 7 figures, updated analysis and tex
Minimal Models for a Superconductor-Insulator Conformal Quantum Phase Transition
Conformal field theories do not only classify 2D classical critical behavior
but they also govern a certain class of 2D quantum critical behavior. In this
latter case it is the ground state wave functional of the quantum theory that
is conformally invariant, rather than the classical action. We show that the
superconducting-insulating (SI) quantum phase transition in 2D Josephson
junction arrays (JJAs) is a (doubled) Gaussian conformal quantum critical
point. The quantum action describing this system is a doubled
Maxwell-Chern-Simons model in the strong coupling limit. We also argue that the
SI quantum transitions in frustrated JJAs realize the other possible
universality classes of conformal quantum critical behavior, corresponding to
the unitary minimal models at central charge .Comment: 4 pages, no figure
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